<html>
<head>
<meta name="viewport" content="width=device-width" />
<style>
    /* font size 
    div {
        font-size: 1em;
        -webkit-transition: font-size 1s ease-out;
    }
    
    div:hover {
        font-size: 4em;
    } */
    div {
        opacity: 1.0;
        -webkit-transition: opacity 1s ease-out;
    }
    
    div:hover {
        opacity: 0.3;
    }
</style>
</head>
<body>
    <div>Hover your mouse over me!</div>
